Eosinophilic Pleuritis

Synonyms

Reactive eosinophilic pleuritis; REP

Definition

Eosinophilic pleuritis is an abundant eosinophilic infiltration of the pleural tissue and fluid. It is often an incidental histologic finding most commonly seen in patients with pneumothorax due to any cause. It has been identified in a large amount of biopsies from patients with spontaneous pneumothorax, and it is thought to be a nonspecific reaction to pleural injury.

In pneumothorax, this reaction is caused by the introduction of air which leads to the disruption of mesothelial cells with subsequent fibrinous exudation. The fibrin creates a meshwork that entraps the eosinophils and histiocytes. In later stages, this is accompanied by the granulation tissue which appears in the underlying pleura. The presence of mesothelium lining the surface and slits within the lesion suggests that mesothelial regeneration eventually develops. This is hypothesized to be either through transformation of free-floating macrophages or underlying...